Compact discs, also known as CD's, are convenient, durable storage devices that are capable of holding large amounts of data. Information on a CD is typically recorded as a series of peaks and valleys located on a reflective metallic layer disposed within the disc itself.
The information stored on a CD is not directly readable by the human eye; a CD player is typically used to access data stored on a given CD. CD players use lasers to "read" CD's, gathering information about the peaks and valleys on the reflective layer of a given disc. This information is processed by an associated computer which then converts the information for use.
Since the data stored on a compact disc is not accessible directly and must be converted before use, it is possible to prevent retrieval of the stored information without physically destroying the entire disc. Altering the disc so as to prevent access to, and conversion, of the stored data will essentially prevent retrieval of the information stored on the disc. In other words, data stored on an "unreadable" disc is often irretrievable.
However, due to advances in technology, the definition of what it means for a disc to be "unreadable" is evolving. It is possible, for example, to retrieve data from very small regions of a damaged compact disc. Data recorded on a CD that is otherwise unreadable with typical CD players may often still be retrieved through the use of specialized machines. As a result, simply making a disc "non-playable" does not necessarily guarantee that the information on the disc is irretrievable. It is possible, by means of special laser reading devices, to retrieve information from small particles of compact discs. Particle size has to be reduced to 0.25 mm before this retrieval method is rendered useless.
To achieve secure destruction of the information on a compact disc, the disc must be altered so that no technology can be employed to access any of the information previously recorded on the disc. As used in this application, the term "secure" destruction of data refers to the destruction of data in a manner that makes the data irretrievable by any means. The irretrievability requirement is of particular importance to government-agencies, especially those agencies involved with issues of national security.
For archival purposes, it is often desirable to retain the disc and label in readable condition, even though destruction of the underlying data is desired. In many instances, the complete destruction of a disc containing sensitive information is not desirable. In some cases, it may be appropriate to keep discs from which no data may be recovered. In situations involving national security, for example, maintaining archives of discs that have been rendered unintelligible will help establish that certain discs have actually been rendered unintelligible, rather than stolen or misplaced. Without an archive of unintelligible, yet identifiable, discs, falsified records may incorrectly indicate that discs with sensitive information have been "destroyed," leading to possible information leaks. This type of archive requires a data destruction system that maintains the media labeling information, while rendering unintelligible the underlying data.
Several approaches have been explored in an attempt to achieve secure destruction of CD data. These approaches have included, among other things, the use of heat, chemical etching compounds, and standard abrasives. Unfortunately, none of these approaches has been adequate. Heating of CD's, for example, resulted in flaking of the information-containing layer. This flaking often produced loose pieces of the disc where the flake size was large enough to allow retrieval of information. Furthermore, chemical etching resulted in the production of noxious fumes which were sufficiently strong to be totally unacceptable in office environments. Abrasives, such as those used in conventional sanders, became so quickly loaded with removed debris that they were rendered useless after only a relatively-short period of use. In fact, early abrasives could not even securely destroy three CD's before the abrasive required replacement. Such a short life span is unacceptable.
Other approaches have used brushes or pads that contact a CD while the CD rotates. Several United States patents have been issued for these devices, as shown in U.S. Pat. Nos. 4,654,918; 4,662,025; and 4,709,437. However, none of the devices described in these patents is directed to the destruction of the information on the CD. They are merely directed to the cleaning of compact discs and, as such, do not accomplish the task of secure destruction.
A device for the secure destruction of CD data must irretrievably destroy the data on the disc without producing noxious fumes and must continue to operate over an extended period of time, having the capacity to destroy the information on more than three CD's.
Primitive abrasive systems that securely destroy the information on some types of CD's have recently been developed. Unfortunately, these abrasive systems are currently only suitable for destroying the information recording surfaces found on read-only CD's, which use aluminum recording surfaces. The abrasive systems used to destroy aluminum-surfaced discs are not satisfactory, however, for newer, recordable CD's which use gold recording surfaces. A new approach to securely destroy data stored on CD's having non-aluminum-based recording surfaces is required.
Thus, what is needed is a compact disc data destruction device that includes advantages of the known devices, while addressing the shortcomings they exhibit. The compact disc data destruction device should alter selected compact discs to destroy the data recorded on the disc so that recovery of the data is prevented. The device should also destroy the information on a compact disc while leaving the associated disc label in a legible format, so that the disc may be identified and accurately stored or discarded as needed. The device should also be clean to use and should not produce noxious fumes. The device should also be useable for an extended period of time, enabling destruction of data on many CD's, regardless of the type of material used for the disc information bearing surface. The device should also be economical and easy to use.